1. Field of the Invention
The present invention relates to an air pillow made of a flexible sheet, such as a vinyl chloride sheet, and adapted to support the neck and head of a user so as to help the user rest or sleep well in, for example, an automobile, an airplane, a train, or a like vehicle.
2. Description of the Related Art
As shown in FIG. 12, a conventional air pillow made of a flexible sheet includes appropriately formed upper and lower sheets. The two cutouts are joined together at their peripheral portions through high-frequency heating. This type of air pillow helps a user rest through support of his/her neck, but is not so formed to provide comfortable support for the back of his/her head. Particularly, when a user sitting in a vehicle recliner uses the air pillow while the recliner is reclined, the air pillow fails to comfortably support the back of his/her head. In recent years, in order to cope with this problem, an air pillow shown in FIG. 13 has been put on the market. The air pillow of FIG. 13 is in an uninflated state and includes appropriately cut upper and lower sheets, each having divided head rest portions. The two cutouts are joined together at their peripheral portions and along the divided head rest portions through high-frequency heating. When the air pillow is inflated, the head rest portions assume the form of pipes. However, the inflated head rest portions and their peripheral portions suffer deformation, such as longitudinal or lateral twist, curvature, or depression. That is, since the upper and lower sheets are joined together directly along the head rest portions through high-frequency heating, the inflation of the head rest portions involves the local occurrence of strong tension, with resultant unexpected deformation. Also, since a limited space is divided into the head rest portions, the inflated pipe-like head rest portions do not contain a sufficient amount of air to comfortably support the back of the head of a user. Thus, from functional and aesthetic points of view, the air pillow is not satisfactory.
An object of the present invention is to provide an air pillow which does not involve any deformation when inflated and which provides comfortable support for the back of the head of a user.
In order to solve uncertainty about the shape which an air pillow assumes when inflated, the present inventors have intensively studied how air pressure influences the structures of pneumatic products made of a flexible material, such as a vinyl chloride sheet, as observed when the products are inflated. On the basis of the thus-obtained findings, the present inventors have accomplished the invention.
The present invention provides an air pillow comprising: a first flexible sheet having a predetermined shape and size; a second flexible sheet having a predetermined shape and size substantially the same as those of the first sheet and joined to the first sheet along its circumferential edge; at least one gusset located in a head rest area of the pillow, the gusset being disposed between and joined to the first and second sheets; and a valve joined to the first or second sheet at a predetermined position and adapted to introduce or release air therethrough.
Preferably, the first and second sheets, the gusset, and the valve are each made of a resin; the second sheet is joined to the first sheet through high-frequency heating; the gusset is joined to the first and second sheets through high-frequency heating; and the valve joined to the first or second sheet through high-frequency heating.
Preferably, two or more gussets are provided in parallel in the head rest area such that the gussets extend in the widthwise direction of the pillow.
Preferably, each of the gussets has the shape of a rectangular tube extending in the widthwise direction of the pillow and has two joint wall portions joined to the first and second sheets, respectively, and two side wall portions extending between the two joint wall portions and defining a maximum distance between the first and second sheets.
Preferably, the maximum distance between the first and second sheets defined by the outermost gusset is smaller than that defined by a gusset adjacent to the outermost gusset.
Preferably, each of the gussets is formed by first and second gusset sheets, the first and second gusset sheets being joined to the first and second flexible sheets, respectively, and joined together along their lateral edges.
Through employment of the gusset(s), the air pillow of the present invention is free of any deformation, such as curvature, twist, or depression, which would otherwise occur at the head rest portion or the neck rest portion. Also, the air pillow can retain a sufficient amount of air in the head rest portion and in the neck rest portion so as to comfortably support the neck and the back of the head of a user. Thus, the invented air pillow exhibits excellent functionality and excellent appearance.